Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<climits>
using namespace std;
int h,w,cont;
char map[55][55];
int d[55][55];
int x[4]={1,0,-1,0},y[4]={0,1,0,-1};
void dfs(int a,int b,int pr)
{
	for(int i=0;i<=3;i++)
	{
		int nx=a+x[i],ny=b+y[i];
		if(map[nx][ny]=='#')continue;
		if(d[nx][ny]<=pr+1)continue;
		//printf("%d %d %d\n",nx,ny,pr+1);
		d[nx][ny]=pr+1;
		dfs(nx,ny,pr+1);
	}
}
int main()
{
	scanf("%d%d",&h,&w);
	for(int i=1;i<=h;i++)
		for(int j=1;j<=w;j++)
			d[i][j]=INT_MAX;
	for(int i=1;i<=h;i++)
	{
		scanf("%s",map[i]+1);
		for(int j=1;j<=w;j++)
			if(map[i][j]=='#')cont++;
	}
	d[1][1]=1;
	dfs(1,1,1);
	if(d[h][w]==INT_MAX)printf("-1\n");
	else printf("%d",h*w-d[h][w]-cont);
}